1. Field of the Invention
The present invention relates to cooling systems for enclosures housing multiple heat-generating electronic components.
2. Description of the Related Art
Computer systems typically include multiple heat-generating electronic components housed in an enclosure. Excessive heat can shorten component lives, so heat must be continually removed from an enclosure to prevent the components from reaching elevated temperatures. In nearly all significant computer installations, the amount of heat that must be removed requires the use of forced convection across or through each of the heat-generating components. Accordingly, the cabinets, chassis and individual components are generally designed to accommodate the forced flow of air through air pathways in or between the components.
An enclosure typically has closed top, bottom, and sides, so that the net airflow is from the front to the rear of the enclosure. Thus, downstream components typically must be cooled by air that has already passed across or through upstream components. For example, in IBM's BLADECENTER chassis (IBM and BLADECENTER are registered trademarks of International Business Machines Corporation, Armonk, N.Y.), air typically enters the chassis or enclosure through multiple server blades and later passes through network switch modules, management modules, and power modules before being drawn through blowers and expelled from the enclosure. The server blades may heat air to as high as 54° C. before the heated air reaches the downstream subsystems toward the rear of the enclosure. As blade and processor technology continues to advance, the operating temperatures of processors and other components will likely increase too. An increase in upstream temperatures may further constrain the downstream modules, making proper cooling even more critical.
One way to help ensure proper cooling of electronic equipment is to increase air flow. However, there are practical limitations on how fast air can be blown through an enclosure. Increased air flow can also lead to other problems, such as increased noise and increased build-up of dust and other contaminants. Another solution to avoid overheating is to design the network switches, power modules, and other downstream components and subsystems to withstand hotter temperatures. Alternatively, limitations may need to be imposed upon the number of server blades supported by the enclosure. Each of these possible solutions has inherent practical limitations.
What is needed is an improved way to cool electronic equipment. In particular, what is need is a better way to cool downstream subsystems that receive pre-heated air. It would be desirable to achieve improved cooling of downstream components without appreciably changing existing constraints. It would be further desirable to improve cooling performance to accommodate future increases in processor speed and power, and to allow for larger numbers of servers within an enclosure.